All quick release axles are made from hardened stainless steel ,and have black aluminium push buttons. Suitable for high end sport wheelchairs. All axles are 1/2″ in diameter. Available in lengths of 130mm, 120mm, 110mm, 114.5mm and 99mm. 12mm diameter axles available on request How To Measure A Quick Release Axle (See Image):- L1 is the length of the wheel hub, measured from the outer faces of the bearings. L2 is the length of the receiver in the chair frame. L1 L2 = Length (L). L is measured from the face of the nut to the front edge of the ball bearing.